The present invention relates to inking rollers for use in printing presses, and more particularly to rollers, such as vibrating rollers and distributing rollers, for use in offset presses, letterpress printing machines, etc. for supplying ink from the ink fountain to the printing portion.
For example in offset presses, ink is supplied from an ink fountain to the printing portion between a blanket cylinder and an impression cylinder by way of a fountain roller, vibrating roller, a plurality of distributing rollers, form roller, plate cylinder and the blanket cylinder. The ink transferred to the blank cylinder is further transferred onto paper, which is the material to be printed on, passed through the printing portion.
The blanket cylinder having the ink applied to the required areas of its outer peripheral surface is pressed against the surface of the paper at the printing portion, so that paper particles on the paper surface adhere to the ink remaining on the surface of the blanket cylinder. The ink portion becoming mixed with the paper particles is transferred to the plate cylinder, form roller, distributing rollers and vibrating roller in succession in a direction opposite to the direction of supply of the ink. Consequently, the ink incorporating paper particles lodges and accumulates especially on the edge portion between the outer periphery of each of the vibrating roller and the distributing rollers and each end face thereof. The deposit of the ink gradually becomes protuberant and hard, so that there arises a need to remove the deposit every day before the printing operation. This work is cumbersome and requires time and labor. In the case where the press has many distributing rollers, the ink removing work is very troublesome.
Proposed in recent years are printing presses which comprise a plurality of vibrating rollers positioned between the fountain roller and the first distributing roller, divided axially of these rollers and arranged at an interval axially thereof so that the quantity of ink to be supplied to the printing portion can be adjusted at positions along the widthwise direction of the paper. Such a press has a large number of vibrating rollers each permitting the ink to lodge and accumulate on opposite end edge portions thereof. The removal of the ink deposit therefore requires very troublesome work. The same problem is encountered also with other types of printing presses such as letterpress printing machines.
An object of the present invention is to overcome the foregoing problem and to provide an inking roller for use in printing presses which is adapted to prevent ink becoming mixed with paper particles from adhering to and accumulating on the edge portions thereof.
The present invention provides a roller characterized in that a nonadhesive layer, which prevents ink or the like becoming mixed with paper particles from adhering, is formed on the roller over an edge portion between an outer peripheral surface of the roller and each of end faces thereof, an end portion of the outer peripheral surface continuous with the edge portion and at least a portion of the end face toward the outer peripheral surface.
Nonadhesiveness is a property of preventing ink or the like becoming mixed with paper particles from adhering. The nonadhesive layer comprises a nonadhesive resin such as tetrafluoroethylene resin or like fluorocarbon resin or silicone resin.
The nonadhesive layer may be formed by adhering to the roller a member at least having a surface formed from a nonadhesive agent and covering the edge portion between the roller outer peripheral surface and each end face thereof, the end portion of the outer peripheral surface continuous with the edge portion and at least the portion of the end face toward the outer peripheral surface, whereas it is especially desirable to form the layer by coating the roller with a nonadhesive agent.
Ink or the like has difficulty in adhering to the nonadhesive layer which is formed on the roller over the edge portion, the outer peripheral surface portion continuous therewith and the end face. It is therefore unlikely that the ink or the like becoming mixed with paper particles will adhere to and accumulate on the roller edge portion.
Thus, the present invention prevents the ink or the like becoming mixed with paper particles from adhering to and accumulating on the edge portion, obviating the need to perform cumbersome ink removing work before printing operation.
The width (axial width) of the nonadhesive layer on the roller outer peripheral surface and the width (radial width) of the layer on the end face are suitably determined from such a range that the paper particle-incorporating ink or the like can be prevented from lodging and accumulating on the edge portion. If too small in these widths, the nonadhesive layer will be ineffective for preventing adhesion and accumulation of the ink, while the effect to prevent adhesion and accumulation of the ink or the like remains the same even if the widths increase beyond a certain value. Accordingly, it is desirable to minimize the widths insofar as the adhesion and accumulation of the ink or the like can be precluded. The layer will not cause any particular trouble even if having a large width on the end face, whereas an excessively large width on the outer peripheral surface is not desirable. Although the minimum width required for preventing the adhesion and accumulation of the ink or the like varies with other conditions such as the size of the roller, the width on the outer peripheral surface is suitably determined, for example, from the range of 0.5 to several millimeters in view of such conditions.
The thickness of the nonadhesive layer, which is preferably smaller, is several micrometers to about 100 micrometers to be satisfactory.